Intratesticular lidocaine reduces the response to surgical castration in dogs

ObjectiveTo investigate whether intratesticular injection of lidocaine pre-surgery would reduce the intraoperative responses to elective castration in dogs.Study designDouble-blinded, randomized, controlled, prospective clinical study.AnimalsForty-two client-owned dogs weighing 2.2–38.4 kg and aged between 4.5 and 56 months.MethodsGroup L dogs received an intratesticular injection of 2% lidocaine (2 mg kg^?1) and Group S an identical volume of saline prior to surgery. Premedication was with acepromazine and morphine intramuscularly. Anaesthesia was induced with propofol intravenously and maintained with isoflurane vaporized in oxygen. Heart rate (HR), mean arterial pressure (MAP), respiratory rate (f_R), end-tidal isoflurane (Fe′ISO) and carbon dioxide concentrations, oxygen saturation and ECG were monitored during surgery. Fe′ISO was maintained at 1.0 ± 0.1%. Supplemental propofol was given in response to gross movement.ResultsGroup L had significantly lower maximum values for both HR and MAP. Group L displayed significantly smaller increases in HR during exteriorization of the first testis than Group S. There was an overall significant difference in MAP between groups during all surgical events (p = 0.041) and time points (p = 0.002). In univariate analysis, Group L showed significantly less changes in MAP during skin incision, exteriorization of the first testis and clamping of both spermatic cords. Group S reached its highest f_R significantly earlier. Group L (eight dogs) required additional propofol 33 ± 18 minutes after the start of surgery and Group S (seven dogs) at 19 ± 17 minutes; this difference was not statistically significant. Seven dogs in Group L and 12 dogs in Group S required rescue analgesia with morphine (GCMPS-SF score ≥6); this difference was not statistically significant. No adverse effects were reported postoperatively.Conclusions and clinical relevanceBased on this study, the authors recommend the use of intratesticular lidocaine for surgical castration in dogs.     

Anaesthetic sparing effect of local anaesthesia of the ovarian pedicle during ovariohysterectomy in dogs

ObjectiveTo evaluate the effect of local anaesthesia of the mesovarium on end-tidal isoflurane (Fe′_iso) concentration and vital parameters during canine ovariohysterectomy.Study designProspective, randomized, blinded study.AnimalsTwenty client-owned dogs undergoing elective ovariohysterectomy. Mean age 1.7 (±0.53, SD) years and mean body weight 21 kg (±5.9, SD).MethodsPre-medication was with intravenous acepromazine (0.02 mg kg⁻¹) and methadone (0.1 mg kg⁻¹). Anaesthesia was induced with propofol and maintained with isoflurane in oxygen. One group (n = 10) received local infiltration of the mesovarium with 0.5 mL lidocaine 2% and one group (n = 10) with 0.5 mL NaCl 0.9%. Heart (HR) and respiratory rates (fr), invasive mean arterial blood pressure (MAP) and Fe′_isowere recorded. The Fe′_iso was adjusted according to changes in HR, RR and MAP. Time points used for comparison were T1 (after induction of anaesthesia before surgery), T2 (after lidocaine infiltration of the mesovarium) and T3 (surgical manipulation of the ovaries). Data were analysed using a mixed model for repeated measurement anova and the Tukey adjustment. Results are presented as mean ± SD; p < 0.05 was considered significant.ResultsIn both groups, HR and fr remained stable at the three time points. Mean values ranged from 84 to 94 beats minute⁻¹ and from 10 to 14 breaths minute⁻¹. The Fe′_iso was significantly lower at T3 compared to T1 and mean values ranged from 0.95% to 1.24%. The mean arterial blood pressure was significantly higher at T3 compared to T1 and mean values ranged from 58 to 96 mm Hg. At none of the time points were there significant differences between the two groups for HR, fr, MAP or Fe′_iso.ConclusionNeither an isoflurane sparing effect nor a difference in autonomic response to surgery was demonstrated following local anaesthesia of the mesovarium.Clinical relevanceThere appeared to be minimal benefit from local anaesthesia of the mesovarium during this study.     

利多卡因、布吡卡因行犬硬膜外阻滞时的药代动力学

为研究利多卡因(lidocaine)和布吡卡因(bupivacaine)行硬膜外阻滞时的药代动力学特征,将16只健康犬随机分成2组(n=8),硬膜外阻滞时按体质量分别注入2%利多卡因6mg/kg和0.5%布吡卡因2mg/kg,在注药后的3、5、8、10、15、20、30、40、50、60、75、90、120、150、180min分别采取股动脉血,用气相色谱法测定血药浓度,比较2组药代动力学指标。结果表明,利多卡因和布吡卡因的药-时曲线均符合一室开放模型,t1/2ka分别为(3.55±0.73)min和(7.76±0.38)min,tpeak分别为(18.8±2.2)min和(35.6±1.5)min,Cmax分别为(4.67±0.37)mg/L和(1.38±0.08)mg/L,AUC分别为(739±73)μg.mL-1.min和(366±45)μg.mL-1.min,CL分别为(12.2±4.6)mL/min和(5.5±0.67)mL/min。     

Propofol and fentanyl infusions in dogs of various breeds undergoing surgery

ObjectiveTo report the cardiovascular variables, anaesthetic effects and recovery quality of an anaesthesia technique using variable rate infusion propofol combined with constant rate infusion fentanyl in dogs undergoing elective surgery.Study designProspective clinical trial.AnimalsA total of 27 dogs, aged 2.7 ± 2.65 years and weighing 24 ± 11 kg.MethodsFollowing intramuscular acepromazine (0.03 or 0.05 mg kg^?1) and subcutaneous carprofen (4 mg kg^?1) pre-medication, anaesthesia was induced with propofol (4.0 ± 0.5 mg kg^?1) intravenously (IV). All dogs were ventilated with 100% oxygen to maintain normocapnia. Propofol was infused at 0.4 mg kg^?1 minute^?1 for 20 minutes and then at 0.3 mg kg^?1minute^?1. If mean arterial blood pressure (MAP) decreased below 70 mmHg, propofol infusion was reduced by 0.1 mg kg^?1 minute^?1. Five minutes after induction of anaesthesia, fentanyl was administered (2 μg kg^?1) IV followed by the infusion at 0.5 μg kg^?1 minute^?1 and atropine (40 μg kg^?1) IV. Heart rate, MAP, respiratory rate, tidal volume, end-tidal carbon dioxide, presence of reflexes, movements and recovery times and quality were recorded.ResultsMean anaesthetic duration was 131 ± 38.5 minutes. Mean heart rate peaked 10 minutes after atropine injection and gradually declined, reaching pre-anaesthetic values at 55 minutes. MAP easily was maintained above 70 mmHg. Mean times to return of spontaneous ventilation, extubation, head lift and sternal recumbency were 21 ± 10.1, 33 ± 14.6, 43 ± 19.7 and 65 ± 23.4 minutes, respectively. Recovery was smooth and quiet. The time to sternal recumbency was significantly correlated with the duration of anaesthesia and total dose of propofol; time to extubation was correlated to total dose of propofol.Conclusion and clinical relevancePropofol and fentanyl infusions provided stable cardiovascular function and satisfactory conditions for surgery. Some modifications of infusion rates are required to improve the long-recovery times.     

Effect of intravenous propofol and remifentanil on heart rate, blood pressure and nociceptive response in acepromazine premedicated dogs

ObjectiveTo investigate the cardiorespiratory, nociceptive and endocrine effects of the combination of propofol and remifentanil, in dogs sedated with acepromazine.Study designProspective randomized, blinded, cross-over experimental trial.AnimalsTwelve healthy adult female cross-breed dogs, mean weight 18.4 ± 2.3 kg.MethodsDogs were sedated with intravenous (IV) acepromazine (0.05 mg kg^?1) followed by induction of anesthesia with IV propofol (5 mg kg^?1). Anesthesia was maintained with IV propofol (0.2 mg kg^?1 minute^?1) and remifentanil, infused as follows: R1, 0.125 μg kg^?1 minute^?1; R2, 0.25 μg kg^?1 minute^?1; and R3, 0.5 μg kg^?1 minute^?1. The same dogs were administered each dose of remifentanil at 1-week intervals. Heart rate (HR), mean arterial pressure (MAP), respiratory rate (f_R), end tidal CO₂ (Pe′CO₂), arterial hemoglobin O₂ saturation, blood gases, and rectal temperature were measured before induction, and 5, 15, 30, 45, 60, 75, 90, and 120 minutes after beginning the infusion. Nociceptive response was investigated by electrical stimulus (50 V, 5 Hz and 10 ms). Blood samples were collected for plasma cortisol measurements. Statistical analysis was performed by anova (p < 0.05).ResultsIn all treatments, HR decreased during anesthesia with increasing doses of remifentanil, and increased significantly immediately after the end of infusion. MAP remained stable during anesthesia (72–98 mmHg). Antinociception was proportional to the remifentanil infusion dose, and was considered satisfactory only with R2 and R3. Plasma cortisol concentration decreased during anesthesia in all treatments. Recovery was smooth and fast in all dogs.Conclusions and clinical relevanceInfusion of 0.25–0.5 μg kg^?1 minute^?1 remifentanil combined with 0.2 mg kg^?1 minute^?1 propofol produced little effect on arterial blood pressure and led to a good recovery. The analgesia produced was sufficient to control the nociceptive response applied by electrical stimulation, suggesting that it may be appropriate for performing surgery.     

A comparison of the effects of two different doses of ketamine used for co-induction of anaesthesia with a target-controlled infusion of propofol in dogs

ObjectiveTo assess the cardiorespiratory and hypnotic-sparing effects of ketamine co-induction with target-controlled infusion of propofol in dogs.Study designProspective, randomized, blinded clinical study.AnimalsNinety healthy dogs (ASA grades I/II). Mean body mass 30.5 ± SD 8.6 kg and mean age 4.2 ± 2.6 years.MethodsAll dogs received pre-anaesthetic medication with acepromazine (0.03 mg kg^?1) and morphine (0.2 mg kg^?1) administered intramuscularly 30 minutes prior to induction of anaesthesia. Heart rate and respiratory rate were recorded prior to pre-medication. Animals were allocated into three different groups: Group 1 (control) received 0.9% NaCl, group 2, 0.25 mg kg^?1 ketamine and group 3, 0.5 mg kg^?1 ketamine, intravenously 1 minute prior to induction of anaesthesia, which was accomplished using a propofol target-controlled infusion system. The target propofol concentration was gradually increased until endotracheal intubation was possible and the target concentration at intubation was recorded. Heart rate, respiratory rate and noninvasive blood pressure were recorded immediately prior to induction, at successful intubation and at 3 and 5 minutes post-intubation. The quality of induction was graded according to the amount of muscle twitching and paddling observed. Data were analysed using a combination of chi-squared tests, Fisher's exact tests, Kruskal–Wallis, and anova with significance assumed at p< 0.05.ResultsThere were no significant differences between groups in the blood propofol targets required to achieve endotracheal intubation, nor with respect to heart rate, noninvasive blood pressure or quality of induction. Compared with the other groups, the incidence of post-induction apnoea was significantly higher in group 3, but despite this dogs in this group had higher respiratory rates overall.Conclusions and clinical relevanceUnder the conditions of this study, ketamine does not seem to be a useful agent for co-induction of anaesthesia with propofol in dogs.     

Effects of graded doses of propofol for anesthesia induction on cardiovascular parameters and intraocular pressures in normal dogs

ObjectiveTo determine the effects of graded doses of propofol on cardiovascular parameters and intraocular pressures (IOP) in normal dogs.Study designProspective, randomized, modified Latin square, cross-over experimental study.AnimalsEleven adult random-source dogs weighing 20.2 ± 5.7 kg.MethodsThere were three treatment groups: propofol 8 mg kg^?1 intravenous (IV) until loss of jaw tone (Group P), propofol until loss of jaw tone +20% (Group P20), and propofol until loss of jaw tone +50% (Group P50). Atracurium 0.1 mg kg^?1 IV was administered in all treatments immediately after the propofol. All dogs received the three treatments in a randomized order, with at least a one week interval between treatments. Direct arterial blood pressure and IOP by applanation tonometry were obtained at baseline, after 5 minutes of pre-oxygenation (before induction), before, and after intubation. Blood gas samples were obtained at baseline, after pre-oxygenation, and before intubation.ResultsThere was no significant difference in IOP readings at any time point among groups. The IOP was significantly higher before intubation versus before induction in all three groups. There was a significantly smaller change in systolic, mean (MAP), and diastolic (DAP) arterial pressures in the P50 group compared with the P group after intubation. There was a significantly smaller change in MAP and DAP in the P50 group compared with the P20 group after intubation. The increase in CO₂ from before induction to before intubation was significantly greater in the P50 group than in the P or P20 groups.Conclusions and clinical relevanceGraded doses of propofol did not affect the increase in IOP observed with propofol induction in normal dogs. Higher doses of propofol are of no apparent additional benefit in animals who cannot tolerate an abrupt increase in IOP but may be of benefit in dogs who cannot tolerate an abrupt increase in blood pressure accompanying orotracheal intubation.     

Effect of fentanyl on the induction dose and minimum infusion rate of propofol preventing movement in dogs

Objective

To determine the effect of fentanyl on the induction dose of propofol and minimum infusion rate required to prevent movement in response to noxious stimulation (MIR_NM) in dogs.